1. Field of the Invention
This invention relates to a motor drive controlling method for an image forming apparatus suitable for an applying apparatus used, for example, in a textile printing machine, and a motor drive controlling apparatus in the image forming apparatus using the same method.
2. Related Background Art
Use has heretofore been made of an apparatus for applying predetermined paint to cloth continuously conveyed by a belt conveyor apparatus, over a predetermined width in a direction orthogonal to the direction of conveyance by the use of an applicator for applying the predetermined paint over a predetermined width. Describing such an apparatus briefly with reference to the accompanying drawings, FIG. 7 is a pictorial perspective view showing the general construction of a mechanism. FIG. 8 is a control block diagram connected to FIG. 7.
Referring first to FIG. 7, a roller 101 is rotatably supported in a base portion, not shown, and the output shaft 105a of a speed reducer 105 mounted on a servo-motor 102 is fixed to one end of the rotary shaft of the roller 101 through a coupling 100. A first encoder 103 is directly connected to the output shaft of the servo-motor 102. An endless belt 106 having its other end supported by a roller, not shown, is extended over the roller 101, and as shown, cloth 107 is stuck on the endless belt 106 so that paint may be applied onto the cloth 107 over a predetermined width W in a direction orthogonal to the direction of conveyance of the endless belt 106 by a paint applying apparatus, not shown.
On the other hand, in FIG. 8, the feedback control of a speed control loop and a position control loop is effected on the basis of a signal outputted from the first encoder 103, and the servo-motor 102 is driven by a predetermined amount each and the roller 101 is rotated in the direction of arrow by a rotational speed decelerated by the speed reducer 105, whereby the paint is applied to the cloth 107 cover an application width W while the cloth 107 is conveyed.
However, according to the conventional drive controlling system described above, an angular transmission error occurs due to the accumulation or the like of backlash occurring among a number of transmission gears for constituting the speed reducer 105. As a result, the amount of rotation of the servo-motor 102 cannot finally be transmitted to the roller 101 and an error occurs to the rotational angle of the roller 101 and thus, it becomes impossible to highly accurately feed the cloth 107 immovably sticked on the endless belt 106, and this has led to the problem that an overlap portion Wa occurs to the application width W over which the paint is to be applied by the applying apparatus or a void portion Wb is created.